using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using SSPCTester.Devices.Config;
using SSPCTester.Devices.Interfaces;

namespace SSPCTester.UI.Services;

public sealed class SafetyMonitorService : IDisposable
{
    private readonly ISafetyDio _safetyDio;
    private readonly IPowerSupply _power;
    private readonly ILoad _load;
    private readonly DeviceOptions _options;
    private readonly UiLogSink _log;
    private readonly ILogger<SafetyMonitorService> _logger;
    private readonly SemaphoreSlim _gate = new(1, 1);
    private Timer? _timer;
    private bool _handlingEmergency;
    private bool _softwareEmergencyActive;
    private bool _disposed;

    public SafetyMonitorService(
        ISafetyDio safetyDio,
        IPowerSupply power,
        ILoad load,
        IOptions<DeviceOptions> options,
        UiLogSink log,
        ILogger<SafetyMonitorService> logger)
    {
        _safetyDio = safetyDio;
        _power = power;
        _load = load;
        _options = options.Value;
        _log = log;
        _logger = logger;
    }

    public bool IsEmergencyActive { get; private set; }
    public bool IsAlarmOutputOn { get; private set; }
    public string StatusText { get; private set; } = "设备故障";
    public string DetailText { get; private set; } = "设备安全监控未启动";
    public event EventHandler? StatusChanged;

    public void Start()
    {
        if (_timer is not null) return;

        var options = _options.Pci2312;
        if (!options.Enabled)
        {
            SetStatus(false, false, "设备故障", "PCI2312 安全监控未启用");
            return;
        }

        int interval = Math.Clamp(options.PollIntervalMs, 50, 10_000);
        _timer = new Timer(OnTimer, null, TimeSpan.Zero, TimeSpan.FromMilliseconds(interval));
        SetStatus(false, false, "设备正常", "正在监控 PCI2312 急停输入");
    }

    public async Task TriggerSoftwareEmergencyAsync(CancellationToken ct = default)
    {
        await _gate.WaitAsync(ct).ConfigureAwait(false);
        try
        {
            _softwareEmergencyActive = true;
            _handlingEmergency = true;
            SetStatus(true, IsAlarmOutputOn, "软件急停已触发", "正在执行软件急停安全关断");
            _log.Add(UiLogLevel.Error, "软件触发报警急停，开始执行报警灯、电源、负载关断。");

            await EnsureSafetyDioConnectedAsync(ct).ConfigureAwait(false);
            await SetAlarmOutputAsync(true, ct).ConfigureAwait(false);
            await TryShutdownPowerAsync().ConfigureAwait(false);
            await TryShutdownLoadAsync().ConfigureAwait(false);
            SetStatus(true, true, "软件急停已触发", "报警灯已接通，电源输出和负载输入已发送关闭指令");
        }
        catch (Exception ex)
        {
            _softwareEmergencyActive = false;
            _handlingEmergency = false;
            _logger.LogError(ex, "Software emergency shutdown failed.");
            _log.Add(UiLogLevel.Error, $"软件急停执行异常：{ex.Message}");
            SetStatus(true, IsAlarmOutputOn, "设备故障", ex.Message);
            throw;
        }
        finally
        {
            _gate.Release();
        }
    }

    public async Task<SafetyResetResult> ResetAsync(CancellationToken ct = default)
    {
        await _gate.WaitAsync(ct).ConfigureAwait(false);
        try
        {
            return await ResetCoreAsync(ct).ConfigureAwait(false);
        }
        finally
        {
            _gate.Release();
        }
    }

    private async Task<SafetyResetResult> ResetCoreAsync(CancellationToken ct)
    {
        var options = _options.Pci2312;
        await EnsureSafetyDioConnectedAsync(ct).ConfigureAwait(false);
        if (await IsEmergencyInputActiveAsync(options, ct).ConfigureAwait(false))
        {
            const string message = "硬件急停按钮仍处于触发状态，无法执行状态重置。请先旋转或释放设备上的急停按钮，确认急停输入复位后再重试。";
            SetStatus(true, IsAlarmOutputOn, "急停已触发", message);
            return new SafetyResetResult(false, message);
        }

        await SetAlarmOutputAsync(false, ct).ConfigureAwait(false);
        _softwareEmergencyActive = false;
        _handlingEmergency = false;
        SetStatus(false, false, "设备正常", "急停状态已重置，报警灯已关闭，正在监控 PCI2312 输入");
        return new SafetyResetResult(true, "急停状态已重置。");
    }

    private void OnTimer(object? state)
    {
        if (_disposed) return;
        _ = PollAsync();
    }

    private async Task PollAsync()
    {
        if (!await _gate.WaitAsync(0).ConfigureAwait(false)) return;
        try
        {
            var options = _options.Pci2312;
            if (!options.Enabled) return;

            if (options.AutoConnect && !_safetyDio.IsConnected)
                await _safetyDio.ConnectAsync().ConfigureAwait(false);

            bool active = await IsEmergencyInputActiveAsync(options, CancellationToken.None).ConfigureAwait(false);
            if (active)
            {
                await HandleEmergencyAsync().ConfigureAwait(false);
            }
            else if (_softwareEmergencyActive)
            {
                SetStatus(true, IsAlarmOutputOn, "软件急停已触发", "等待状态重置，电源和负载不会自动恢复");
            }
            else if (IsEmergencyActive || IsAlarmOutputOn)
            {
                SetStatus(true, IsAlarmOutputOn, "急停已触发", $"DI{options.EmergencyInputChannel} 已复位，请点击状态重置关闭报警灯");
            }
            else
            {
                SetStatus(false, false, "设备正常", $"DI{options.EmergencyInputChannel} 未触发");
            }
        }
        catch (Exception ex)
        {
            _logger.LogWarning(ex, "Safety monitor poll failed.");
            SetStatus(IsEmergencyActive, IsAlarmOutputOn, "设备故障", ex.Message);
        }
        finally
        {
            _gate.Release();
        }
    }

    private async Task HandleEmergencyAsync()
    {
        if (_handlingEmergency) return;
        _handlingEmergency = true;
        SetStatus(true, IsAlarmOutputOn, "急停已触发", "正在执行安全关断");
        _log.Add(UiLogLevel.Error, "检测到急停输入接通，开始执行报警灯、电源、负载关断。");

        try
        {
            await SetAlarmOutputAsync(true, CancellationToken.None).ConfigureAwait(false);
            await TryShutdownPowerAsync().ConfigureAwait(false);
            await TryShutdownLoadAsync().ConfigureAwait(false);
            SetStatus(true, true, "急停已触发", "报警灯已接通，电源输出和负载输入已发送关闭指令");
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Emergency shutdown failed.");
            _log.Add(UiLogLevel.Error, $"急停关断执行异常：{ex.Message}");
            SetStatus(true, IsAlarmOutputOn, "设备故障", ex.Message);
            _handlingEmergency = false;
        }
    }

    private async Task TryShutdownPowerAsync()
    {
        try
        {
            if (!_power.IsConnected && _options.PowerSupply.AutoConnect)
                await _power.ConnectAsync().ConfigureAwait(false);
            if (_power.IsConnected)
                await _power.OutputAsync(false).ConfigureAwait(false);
            _log.Add(UiLogLevel.Warning, "UDP5080 电源输出已发送关闭指令。");
        }
        catch (Exception ex)
        {
            _logger.LogWarning(ex, "Power shutdown failed.");
            _log.Add(UiLogLevel.Error, $"UDP5080 电源关闭失败：{ex.Message}");
        }
    }

    private async Task TryShutdownLoadAsync()
    {
        try
        {
            if (!_load.IsConnected && _options.Load.AutoConnect)
                await _load.ConnectAsync().ConfigureAwait(false);
            if (_load.IsConnected)
                await _load.InputAsync(false).ConfigureAwait(false);
            _log.Add(UiLogLevel.Warning, "IT8702P 负载输入已发送关闭指令。");
        }
        catch (Exception ex)
        {
            _logger.LogWarning(ex, "Load shutdown failed.");
            _log.Add(UiLogLevel.Error, $"IT8702P 负载关闭失败：{ex.Message}");
        }
    }

    private async Task<bool> IsEmergencyInputActiveAsync(Pci2312Options options, CancellationToken ct)
    {
        bool value = await _safetyDio.ReadInputAsync(options.EmergencyInputChannel, ct).ConfigureAwait(false);
        return options.EmergencyInputActiveHigh ? value : !value;
    }

    private async Task SetAlarmOutputAsync(bool on, CancellationToken ct)
    {
        var options = _options.Pci2312;
        bool outputValue = options.AlarmOutputActiveHigh ? on : !on;
        await _safetyDio.WriteOutputAsync(options.AlarmOutputChannel, outputValue, ct).ConfigureAwait(false);
        IsAlarmOutputOn = on;
    }

    private async Task EnsureSafetyDioConnectedAsync(CancellationToken ct)
    {
        var options = _options.Pci2312;
        if (!options.Enabled)
            throw new InvalidOperationException("PCI2312 安全输入输出未启用，无法控制报警灯。");

        if (!_safetyDio.IsConnected)
            await _safetyDio.ConnectAsync(ct).ConfigureAwait(false);
    }

    private void SetStatus(bool emergencyActive, bool alarmOutputOn, string statusText, string detailText)
    {
        IsEmergencyActive = emergencyActive;
        IsAlarmOutputOn = alarmOutputOn;
        StatusText = statusText;
        DetailText = detailText;
        StatusChanged?.Invoke(this, EventArgs.Empty);
    }

    public void Dispose()
    {
        _disposed = true;
        _timer?.Dispose();
        _gate.Dispose();
    }
}

public sealed record SafetyResetResult(bool Success, string Message);